Hexamethyldisilazane (HMDS) is an important organosilicon compound widely used in pharmaceutical manufacturing, semiconductor processing, organic synthesis, and industrial surface modification. Understanding its physical and chemical properties helps businesses identify suitable material grades for specific production requirements. For procurement professionals, evaluating these characteristics is equally important when selecting reliable Hexamethyldisilazane HMDS Manufacturers who can provide consistent product quality, technical specifications, and dependable supply.
What Is Hexamethyldisilazane (HMDS)?
Hexamethyldisilazane, commonly abbreviated as HMDS or HMDZ, is an organosilicon chemical belonging to the disilazane family. It is also known as bis(trimethylsilyl)amine and is identified by CAS number 999-97-3.
Its molecular formula is C6H19NSi2, with a molecular weight of approximately 161.39 g/mol. HMDS contains two trimethylsilyl groups connected through a nitrogen atom, making it useful as a silylating reagent in various chemical reactions.
The compound is valued for its ability to introduce trimethylsilyl groups into suitable substrates, supporting applications in pharmaceutical synthesis, analytical chemistry, and material surface treatment.
Physical Properties of Hexamethyldisilazane
The physical characteristics of HMDS influence its handling, storage, purification, and suitability for different industrial applications.
1. Appearance and Physical State
HMDS is generally supplied as a clear, colourless liquid with a characteristic ammonia-like odour. Its liquid form makes it convenient for controlled dosing, chemical processing, and industrial applications.
Buyers should examine the appearance specifications provided by the manufacturer to identify visible contamination, unusual colour changes, or other deviations from the expected product characteristics.
2. Boiling Point
Hexamethyldisilazane has a typical boiling point of approximately 125–126°C at atmospheric pressure.
This property is relevant to purification, distillation, and process design. Industrial manufacturers consider boiling behaviour when separating HMDS from residual reactants and unwanted volatile components.
3. Density
The density of commercial HMDS is approximately 0.77 g/cm³ at 20°C, although the exact value depends on the measurement conditions and product specification.
Density is an important parameter for industrial buyers because it supports volume-to-mass calculations, formulation planning, and incoming material quality checks.
4. Melting and Freezing Point
HMDS has a typical freezing point around -76°C to -78°C. Its low freezing temperature allows it to remain liquid across a broad range of ordinary industrial operating temperatures.
However, storage and handling conditions should always follow the manufacturer's recommendations and the applicable Safety Data Sheet.
5. Vapour Pressure and Volatility
HMDS has measurable vapour pressure at room temperature, making ventilation and exposure control important during industrial handling.
Its volatility also influences transfer operations, packaging requirements, and process conditions. Buyers should review the relevant safety documentation before incorporating the chemical into manufacturing operations.
Chemical Properties of Hexamethyldisilazane
The chemical structure of HMDS gives it several useful characteristics, particularly in silylation reactions and surface modification.
1. Silylating Behaviour
One of the most important chemical properties of HMDS is its ability to act as a silylating reagent. It transfers trimethylsilyl groups to suitable compounds containing reactive hydrogen atoms.
This functionality makes HMDS useful in organic synthesis, pharmaceutical intermediate production, and analytical derivatisation processes.
2. Moisture Sensitivity
HMDS reacts with water through hydrolysis, producing trimethylsilanol and ammonia. Therefore, moisture exposure can influence its chemical composition and overall product quality.
Industrial buyers should pay attention to moisture specifications, container integrity, and storage recommendations when sourcing this material.
3. Solubility Characteristics
HMDS is practically insoluble or poorly miscible with water but is soluble in several organic solvents. Its solvent compatibility makes it useful in selected organic synthesis and surface-treatment processes.
The exact compatibility should be evaluated against the intended formulation and process conditions.
4. Chemical Stability
Under recommended storage conditions, HMDS can maintain its quality when protected from moisture and incompatible substances. Contact with water and unsuitable reactive chemicals should be avoided.
Manufacturers and industrial users should follow the product-specific SDS for stability, incompatibility, and handling information.
Important Physical and Chemical Specifications of HMDS
For industrial buyers, understanding the typical specifications of HMDS makes it easier to evaluate supplier documentation and product suitability.
The commonly referenced physical and chemical characteristics include:
- Chemical name: Hexamethyldisilazane.
- Common abbreviation: HMDS or HMDZ.
- CAS number: 999-97-3.
- Molecular formula: C6H19NSi2.
- Molecular weight: Approximately 161.39 g/mol.
- Appearance: Clear, colourless liquid.
- Odour: Ammonia-like.
- Boiling point: Approximately 125–126°C at atmospheric pressure.
- Density: Approximately 0.77 g/cm³ at 20°C.
- Freezing point: Approximately -76°C to -78°C.
- Refractive index: Approximately 1.409.
- Flash point: Typically around 11°C, depending on the test method and product specification.
These are indicative reference values rather than guaranteed specifications for every commercial grade. Actual values and acceptance limits should be confirmed through the manufacturer's current Technical Data Sheet (TDS) and batch-specific Certificate of Analysis (COA).
Industrial Applications Based on HMDS Properties
The combination of its silylating behaviour and organosilicon structure makes HMDS valuable across multiple industries.
- Pharmaceutical manufacturing: Used as a silylating reagent in selected pharmaceutical synthesis and intermediate production processes.
- Semiconductor industry: Applied as a surface adhesion promoter during photoresist processing and photolithography.
- Organic synthesis: Supports chemical derivatisation and silylation reactions.
- Surface modification: Helps introduce hydrophobic characteristics to suitable silica and inorganic surfaces.
- Specialty chemicals: Used in selected material modification and organosilicon chemistry applications.
These applications make product consistency and specification control important considerations for industrial procurement teams.
What Should Industrial Buyers Check When Selecting HMDS Manufacturers?
When evaluating Hexamethyldisilazane HMDS Manufacturers, buyers should look beyond the advertised purity percentage. Important considerations include chemical assay, moisture content, impurity profile, analytical testing, batch consistency, packaging, and technical documentation.
A reliable manufacturer should be able to provide relevant product specifications, a Technical Data Sheet, a Safety Data Sheet, and a batch-specific Certificate of Analysis, as applicable.
Industrial buyers should also verify whether the available grade meets their intended application requirements. Semiconductor processing, pharmaceutical synthesis, and general industrial applications may require different quality parameters.
Source Hexamethyldisilazane from Connex Pharma
Connex Pharma offers Hexamethyldisilazane (HMDS / HMDZ) as part of its specialty chemical product portfolio. Businesses looking for HMDS for pharmaceutical, specialty chemical, and industrial applications can explore the company's product information and enquire about applicable specifications, availability, and commercial supply requirements.
Visit the Hexamethyldisilazane HMDS Manufacturers in India page to learn more about Connex Pharma and its HMDS offering.
Conclusion
Understanding the physical and chemical properties of Hexamethyldisilazane is essential for selecting the right material for industrial applications. Parameters such as molecular weight, boiling point, density, moisture sensitivity, solubility, and silylating behaviour influence its handling and performance across different manufacturing processes.
Choosing experienced Hexamethyldisilazane HMDS Manufacturers can help businesses establish consistent sourcing arrangements and reduce quality-related procurement challenges.
For industrial buyers, evaluating these characteristics alongside product specifications, quality documentation, and manufacturing consistency is important when choosing an HMDS supplier. Working with a capable manufacturer helps support dependable chemical sourcing and application-specific quality requirements.
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